Self-lubing material inspired by earthworms
Even if you're grossed out by earthworms, you have to admit that the things are usually quite clean, despite the fact that they live in the dirt. That's because they're constantly secreting a lubricating layer of mucus, which keeps that dirt from sticking. Scientists have now replicated that quality in a new material that could have numerous applications.
Created by a team at Germany's Leibniz Institute for New Materials, the rubbery polymer material has tiny pores in its surface, and contains droplets of silicone oil.
Ordinarily, that oil stays inside the polymer. When pressure is applied, however, the droplets change shape, allowing them to seep out through the pores and onto the material's surface. There, they form a lubricating layer which is continuously replenished as it gets wiped off against its surroundings.
Interestingly, the surface of the polymer is rough, not smooth. This actually adds to the lubricating effect, as it allows the oil to better adhere to the polymer, forming a thicker layer than would otherwise be possible. In fact, when both rough and smooth versions of the material were tested, the oily film on the rough surface lasted for approximately 10,000 friction cycles, whereas the film on the smooth surface lasted for only about 300.
The material could conceivably find use in any situation where objects need to slide past or through solid structures, plus it may also have biomedical applications, as microbes growing on its surface would be continuously sloughed off.
A paper on the research, which was led by Dr. Jiaxi Cui, was recently published in the journal Advanced Materials.